#### Answer

Not one-to-one

#### Work Step by Step

We know that a function is one-to-one if each x-value of the function corresponds to only one y-value and each y-value corresponds to only one x-value.
The given function is $y=3$, which is a horizontal line, such that y is equal to 3 for all x-values. Therefore, this function is not one-to-one, because the y-value of 3 corresponds to more than one value of x.